(a) Field of the Invention
The present invention relates to an assembling machine for Ni-MH batteries and an assembly process thereof, more particularly, to an automated assembling machine for a negative electrode plate NI-MH battery which is a secondary battery and the assembly process using the assembling machine thereof.
(b) Description of the Related Art
With the rapid increase in the spread of portable devices such as personal communication systems and notebook computers, there has bee a demand for the development of secondary batteries that are compact, lightweight, and have high energy density. The introduction of environmentally friendly zero-emission electric vehicles have also resulted in the further demand for the development of secondary batteries as power sources.
Batteries generally convert chemical energy into electrical energy by the electric potential difference between metals, and can be classified as primary (nonrechargeable) batteries, secondary (rechargeable) batteries, and special batteries such as solar cells. Primary batteries can be further classified as manganic cell, alkaline cell, mercuric oxide cell, and silver oxide cell batteries depending on the type of electrode, while secondary batteries can be classified as Ni-MH batteries using metal-hydroxide as the electrode, sealed nickel-cadnium batteries, lithium-metal batteries, lithium-ion batteries, and lithium-polymer batteries.
While primary batteries have disadvantages such as short life, low capacity, and nonrechargeability, secondary batteries have excellent performance characteristics for electric vehicles due to their high capacity and long life. Ni type batteries are widely used as secondary batteries because they have proven to have good recycling characteristics and environmental performance.
However, the above Ni type batteries, especially Ni-MH batteries have the disadvantage of low production efficiency that results from a large number of operational steps and a long lead time due to manual assembly operations.
FIG. 1 shows the production process for the negative electrode plate for Ni-MH batteries with previously employed manual assembly operations consisting of seven operational steps.
As indicated in FIG. 1, a line operator pulls by hand a predetermined length negative electrode plate 103 from a negative electrode plate roll 101 and cuts it with a hand cutter. After the cut negative electrode plate 103 is transferred to a rubber table, a line operator marks a boundary of an active material removal area 105 using an engraver, removes the active material of an active material removal area 105 using a manual hammer, and cuts a predetermined length of Ni foil for a tab 107 using a cut-off machine. The corner folded with two Ni foil pieces is weld using a welding machine in a process where a pair of welded Ni foil pieces 107 are positioned at the active material removal area 105 of the negative electrode plate 103 and four corner points of the folded area are temporarily welded using the welding machine. The temporarily weld electrode plate 103-1 is fully welded using a direct current resistance welding machine, and a final electrode plate 103-2 is then blanked using a blanking press.
However, as the above assembly process for a negative electrode plate for Ni-MH batteries by previously employed manual assembly operations is dependent on manual operations using manual tools, the total manufacturing expense and product reject rate is high due to a large number of assembly operational steps.